近日，香港理工大学朱叶团队报道了A位层状有序钙钛矿的本征极涡晶体。2026年4月29日出版的《自然》杂志发表了这项成果。

拓扑相由其拓扑不变量表征，被认为是与普通相不同的物质态，并有望在人工智能时代作为微小而鲁棒的信息载体。然而，这些非平庸态通常在非平衡条件下发现，或通过外部的电学或力学边界约束而稳定，这限制了它们的应用。特别是在铁电体中，通常需要由界面束缚电荷产生的最大退极化场来平衡原子尺度偶极涡旋所需的大弹性能和梯度能。尽管人们做了大量尝试，但在块体铁电体中实现高度有序的拓扑极性晶体仍然是一个挑战。

研究组展示了一种二维极性刺猬晶格，其周期小至4纳米，可在A位层状有序钙钛矿家族中自发结晶，不受任何外部边界约束。利用先进扫描透射电子显微镜，研究组在实空间中观察到了极性刺猬涡旋，并揭示了其物理本质——调制后的同相和反相八面体旋转的协同组装，而杂化非本征铁电性进一步支撑了这一机制。理论计算表明，描述八面体旋转的声子交换相互作用是这种有趣偶极拓扑结构的主要驱动力。该发现不仅澄清了层状有序钙钛矿中广泛存在的超晶格在结构和起源上的模糊认识，而且为设计钙钛矿之外的非平庸结构和功能提供了一个可行的框架。

附：英文原文

Title: Intrinsic polar vortex crystals in A-site layer-ordered perovskites

Author: Xu, Chao, Luo, Nengneng, Yue, Junyi, Chen, Changsheng, Bian, Tieyuan, Zhang, Chi, Che, Xiangli, Liang, Jianwen, Li, Molly Meng-Jung, Yin, Jun, Chen, Zhen, Zhang, Shujun, Pan, Xiaoqing, Zhu, Ye

Issue&Volume: 2026-04-29

Abstract: Topological phases, as characterized by their topological invariants, have been considered as distinct states from the raw phases and hold great promise as tiny yet robust information carriers for the era of artificial intelligence1,2. However, these nontrivial states are typically found under non-equilibrium conditions, or stabilized by extrinsic electrical or mechanical boundary constraints3,4,5,6, which limit their applications. Particularly in ferroelectrics, it usually entails a maximized depolarization field produced by interfacial bound charges to balance the large elastic and gradient energies as dipole whirling at the atomic scale7,8,9,10. Despite substantial attempts, achieving highly ordered topological polar crystals in bulk ferroelectrics still remains a challenge11,12,13,14. Here we show that a two-dimensional polar hedgehog lattice with a period down to 4nm can crystallize spontaneously free from any external boundary constraints in a family of A-site layer-ordered perovskites. Using advanced scanning transmission electron microscopy, we observe the polar hedgehog vortices in real space and disclose the physical nature as the cooperative assembly of modulated in-phase and out-of-phase octahedral rotations, further underpinned by hybrid improper ferroelectricity. Theoretical calculations show that the exchange interaction of phonons describing the octahedral rotations is the primary driving force of this intriguing dipole topology. Our findings not only clarify the ambiguity in the structure and origin of the widespread superstructure in layer-ordered perovskites but also demonstrate a viable framework for designing nontrivial structures and functionalities beyond perovskites.

DOI: 10.1038/s41586-026-10470-2

Source: https://www.nature.com/articles/s41586-026-10470-2